Engineering of an Isoreticular Series of CALF-20 Metal-Organic Frameworks for CO2 Capture

A series of linker-substituted ultramicroporous CALF-20 metal-organic frameworks (MOFs) were built in silico, and their CO2 capture performances over N-2 in flue gas conditions were systematically computationally explored. Among the various linker substitutions explored, squarate-linker-incorporated CALF-20 (SquCALF-20) was demonstrated to show a larger CO2 uptake at 0.15 bar (3.6 mmol/g) and higher CO2/N-2 selectivity (500) in dry conditions compared to pristine CALF-20. Interestingly, this MOF was shown to maintain a high level of CO2 capture performance even in the presence of humidity, although it starts to adsorb H2O at lower relative humidity compared to CALF-20. Because squaric acid is a semiconductor industry feedstock and the few-already published squarate-based MOFs are chemically robust, this engineered SquCALF-20 offers a promising avenue for cost-effective CO2 capture via physisorption, with potential applications in addressing environmental concerns associated with CO2 emissions.